Airports contain a wide variety of equipment which air traffic control personnel use to aid in the process of launching and recovering aircraft in a safe and efficient manner. Typically, each user interface to this equipment is unique, because there is no common manufacturer and because each equipment component performs a different function. Such an equipment interface may be as simple as a panel of push buttons with incandescent lamps or as complex as a rack of switches and LEDs. Such equipment and interfaces may include runway lights, instrument landing systems (ILS), emergency generators, and other systems that ensure safe management of the aircraft. In the past interfaces were often located in different places in and around the airport, such as the control tower cab, scattered equipment cabinets, or at field locations on or off the runway. The inability to control air traffic, navigational, and visual aids in a single interface creates a clear safety deficit. Additionally, often times different airports have different equipment and interfaces, with the result that even air traffic personnel having long professional experience at one airport would potentially have a long and difficult time learning the systems and interfaces at a different airport.
To improve the reliability and consistency of air traffic control systems, systems and methods have been proposed and implemented to connect all of these various interfaces to a common high-speed network known as an Integrated Control and Monitor System (ICMS) manufactured by the assignee of this application. See, U.S. Pat. No. 6,604,030, hereby incorporated herein by reference in its entirety. The advantage of ICMS is that it allows many the interfaces to be displayed to a controller at a common location a in a graphical user interface (GUI) format that has a common “look and feel”. It also allows the controller to selectively control and monitor the equipment from one or more locations. The ICMS further allows the provision of computer controlled interlocks to prevent human error. For example, each physical runway at an airport represents two virtual runways, one handling traffic in one direction, the other handling traffic in the opposite direction. Each of these virtual runways has its own set of equipment. It is therefore imperative that when the traffic direction on a physical runway is changed, ICMS refuses to turn on the equipment for the new virtual runway until the equipment (for example the localizer and the glide slope transmitters) of the previous virtual runway has shut down.
However, the use of software-controlled safety interlocks, such as software-controlled ILS interlocks alone is, while highly reliable, still not absolutely fail safe. Thus, there is still a need for an ILS interlock, preferably capable of interacting with, and as a component of an airport integrated control and monitoring system for runway navigational and safety equipment, that is substantially incapable of permitting the simultaneous activation of such equipment on opposing or conflicting runways.